This is the main cause of failed corporate acquisitions, according to the HR chief of a billion-dollar company

When Ken Brown joined Legrand, North America (LNA) in 2014, it
was nine months into an acquisition that was going poorly.

"The leadership of that acquisition, who had signed on to stay on
and lead their organization through the transition, woke up to
the reality that they weren't going to control everything in the
new world," he told Business Insider.

These cofounders left and the rest of the company was uneasy.

LNA is a billion-dollar subsidiary of Legrand, a world leader in
electrical equipment, and it has been growing aggressively
through acquisitions in the past five years. A failed acquisition
would be disastrous.

Brown took a deep look at the reasons for the struggle and came
to a simple conclusion: A failed integration of a company
is primarily based on miscommunication during the negotiation and
planning phase.

After many long hours of planning and negotiation, a corporate
acquisition is agreed upon, but the way a culture is adapted is
crucial to whether the partnership succeeds or fails. This is
especially true when a company acquires one that is very
different from itself in fundamental ways, like
Walmart and newly purchased Jet.com.

In the specific case Brown investigated at the start of his
tenure at Legrand, he found that both LNA and the smaller company
had paid each other "lip service" to try to make the integration
seem as painless as possible. Both sides were being dishonest
with each other. "I think we went in and said nothing is going to
change, and then immediately things started to change," Brown
said. "Oftentimes it isn't the what but the
how."

Brown met with LNA's CEO John Selldorff and the two eventually
agreed that Brown would institute a culture of "change
leadership" across LNA, which was so heavily reliant on
successful acquisitions at this point in its history.

Brown said it is key to understand that a company's leadership
that says it is "all in" with the deal cannot be taken at its
word. "People are going to fall into three different buckets:
early adopters, people who opted out and are demonstrating
disruptive behavior, and then the vast majority are going to sit
on the fence and wait and see what happens," he explained. It is
necessary to determine which of these applies to a leader in
question and act accordingly.

LNA's HR department created a system for educating an
acquisition's leadership on how the integration was going to
unfold. "People are very clear that we may not be able to tell
you all the answers to all the questions that you have, but we
can tell you how those answers will be determined and what your
role in that will be," Brown said. "So in other words, change
will not happen to you, it'll happen either with you or by you."

The training sessions have been very successful, Brown said, and
LNA even had a chance to bring in the current leadership of the
acquired company that was failing when he first joined. They told
him, "Boy, it would have been wonderful to have this kind of a
session right on the outset," he said.

"That's been a great transformation to see leaders in that
organization, who were feeling victimized after their top
leadership left, now taking the reins and helping guide the rest
of the organization through change."